Telephone-exchange system.



1. L.` WRIGHT',

TELEPHONE EXCHANGE lSYSTEM.

APPLICATIONIILED SEPT-16.. |914.

L234246. l Patented July 24, 1917. l v

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J. L. WRIGHT. ELEFHONE EXCHANGE SYSTEM.

APPLICATION FILED SEPT-16.1914. l

' Patented July 24, 1917.

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J. L. WRIGHT. TELEPHONE EXCHANGE SYSTEM.

Patented July 24, 1917.

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JOSEPH L. WRIGHT, OF CLEVELAND, OHIO, ASSIGNOR, BY MESNE ASSIGNMENT-S, TO WESTERN ELECTRIC COMPANY, INCORPORATED, A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters atent.

`Patented July 21, 1917.

Application led September 16, 1914. Serial No. 862,012.

To all 'whom t may concern Be it known that I, Josnrn L. l/VRIGHT, a citizen of the United States, residing at Cleveland, in the county. of Cuyahoga and State of Ohio, have invented certain new and useiul Improvements in Telephone- Exchange Systems, ot which the following is a specification.

My invention relates to telephone exchange systems, especially to types employing automatic switching mechanism for effeet-ing connections between subscribers.

ln systems ol' these types it is common practice to have automatic selection of trunks by what are termed selector switches.

The object or my invention is to provide means wherein the uniform use of the various trunks is obtained so that the wear on all of the apparatus will be the same.

n. system for dividing the work among the various trunks is shown in Patent No. 831,876 to Keith, September 25, 1906. This patent shows the various selector switches arranged in groups and the corresponding bank contacts of the diilerent groups connected to dis-similar trunks. In other words, one group of switches to select No. 1 trunk would only step to the first contact, while another group of switches to select the same trunk would have to step to No. 10 contact, and so on. This arrangement prevents uniform wiring and makes it necessary to have the various trunks connected to dissimilar contacts in the various groups of switches.

rlhis method of wiring also allows idle trunks to be selected with a minimum number or' steps of the switches. ln other words, under ordinary conditions an idle trunk is selected within two or three steps of the switches and, consequently, the other con tacts in the bank will be very seldom used and will accumulate dust and dirt which may interfere with proper connections when they are used.

`W1ith my invention uniform use of the trunks and of the various contacts is secured.

When all of the apparatus in a particular group is idle the last contact is the only one selectable. After the last contact in a row or group is selected then the contact immediately preceding it is rendered selectable, and after that 'particular contact is selected the next preceding contact is rendered selectable, and so on. Supposing for instance that No. 7 contact is selected and while in use, contacts 8, 9 and 10 are released and rendered idle, then the next contact selectable will be No. 6. This method of selection is continued until the first contact is selected, whereupon No. 10 Contact again becomes selectable if not in use.

For purpose of illustration I have shown my invention as applied to a full automatic system of the Strowger type, but, of course, the invention is applicable to any type of system employing switches for automatic selection of idle trunks.

My invention is illustrated in the accompanying drawings, wherein Figure 1 shows the manner in which uniform selection ot trunks is secured.

Fig. 2 shows a subscribers station, a iirst selector switch and a connector switch of the well known Strowger type.

Fig. 3 is a modilication of Fig. 1.

Referring to Fig. 2, the first selector switch is provided with the usual rotary, vertical and test wipers 64;, 61 and 8st respectively. These wipers are iirst moved in a vertical direction by predetermined impulses and then automatically in a rotary direction to select an idle trunk. The impulses at the subscribers'station are con trolled4 by the operation of the push buttons 51 and 55.

I have not shown the details of the subscribers station as it consists of the usual talking set and sending device mechanism.

For simplicity l have irepresented the sending device mechanism by the two push buttons 51 and 55. Button 51 transmits the vertical or directive impulses while button 55 transmits the rotary or test impulses.

The simultaneous operation of the two buttons causes the release of the automatic switches.

The selector switch and circuits are of the type shown in Patent No. 815,321 to Keith and Erickson, March 13, 1906, while the connector switch and `circuits are of the type shown in Patent No. 815,176 to Keith detail description oi'the circuits 'l have used tor illustration. f

lThe verticalrelay magnet M which in turnl causes the switch shaft carrying the wipers to step 1n a ver'- tical direction. The rotary magnet M is controlled by the rotary relay L and causes the switch shaft tok step in a rotary direction and automatically select an i'dletrunk.

lllhile an idle. trunk is being selected the test relay O remains in an energized condition in series with the back release relay l). This latter relay is ot very low yresistance and will not operate inseries with 'the winding ot relay O. Relay O remains energized while an idle trunk is being selected, due to the tact that the busy contacts over ywhich the test wiper k84; passes are grounded. As ysoon ask ank idle trunk is found, or when a nonbusy contact 1s en` test relay O becomes deenergized and the switch wipers come to rest on contacts leading to an idle trunk. lVhile relay O is energized the circuit of the rotary magnet N is maintained closed in order to keep the switch wipers rotating. As

gaged, then the soon as relay t) becomes denergized the circ kcuit ot the rotary magnet N is broken `and the side switches as usual in the Strowger system assume their final position.

In assuming this position the 'rotary and kvertical relays K andL are disconnected as well as the test relay O. llVhen' relay 0 is disconnected relay P has its winding connected'directly to ground through the side switch'arm :201,'thereby rendering the selected test contact busy against other calls.

Aiter thefrst selector switch engages an idle trunk or connector, impulses are. transmitted by the subscribers sending device to cause the connector switch shaft carrying the wipers 78, 69 and 91 to first step in a vertical direction to the desired row and then step in a rotary direction to select the contacts ot the calling line.

Relays S and T are the vertical and rotary relays respectively, which respond to the impulses transmitted by the subscribers sending device. The vertical magnet U in operating causes the switch to step in a vertical direction, and after the rotary impulse is transmitted the side switch arms move to the second position, thus disconnecting` the vertical magnet and in its place connecting the rotary magnet V. rl`hey next series of impulses cause the rotary magnet to be operated, thereby allowing the switch to rotate and select the contacts et the called tor line.

ritter the contacts` of thisv line are selected the test impulse is transmitted, which causes the rotary relay T to be operated which in turn operates the private relay X and connects the release magnet Z directly to the test wiper 91. lf this test wiper is engaging K controls the vertical ak busyy or grounded contact' the release inagnetZ will operate and restore the connector switch. It, however, the called for line is not busy then causethe side third or final positions. positions the action ot the side switch arms disconnect the rotary and release magnets but connect the ringing relay and also conswitch arms to assume their nects the rotary and vertical conductors lead-y ing trom the wipers of the first selector switch tothe wipersofthe connector switch. c n The calling subscriber operating the push button 51 operates the yringing relay '-Y which was substituted or'the rotary magln taking the iinal the test'impulse will simply o net and causes ringing current from geuerator llOto be applied to thieycalled line.y

ln this particulary instance l have not shown a substation ot a called line, but simply the conductors TO and Ill which eX- tend to the called line. The equipment ot the called line is the saine as that of the calling line.

ln the system shown each line is provided with a iii-st selector switch and it follows that when connection is effected with the called line that the bridge cut-oil relay such as lt is operated.

The `operation ot this relay which is controlled over the test wiper 91 ot the con ncetor, serves to ydisconnect the rotary and vertical relays from theline wires to allow a clear circuit to the called sub-station.

it the termination ot a kconversationythe. calling subscriber in replacing his receiver causes an impulseto be transmitted to both conductors at the saine instant, thereby causing the restoration ot the connector and the iirst selector switches in the usual manner. n

From the foregoing description it will be seen that the selector switch in order to select an idle` trunk rotates until the test wiper S4 finds a test contact which is not grounded.

Referring now to Figi, have shown a set of test contacts number l to l0 inclusive which are multipled and represent a certain group. Each set of mulir [ple contacts, eX- cepting llo. 10 set, are normally connected to ground through the back contacts of relays A, B, C, D, E, F, (l, H and l respectively. No.` l0 set ot' contacts is connected directly to the winding ot' relay J.

lVe will assume that a series ot impulses have been transmitted by the subscriber Vandr that the wipers are in line with the proper row of bank contacts and that the test impulse has been transmitted. Under these conditions the test relay @X will remain energized in series rwith the back release relay PX. rrlhese relays OX and PX correspond to relays P and X ot Fig. Q. Relay OX will remain energized while the test wiper passes over thetirst 9 contactswhich llO being are rendered unselectable by ground being connected respectively through the contacts of relays A to I inclusive. When No. 10 contact is reached the test relay 0X will become denergized and cause the side switch arm 201 to assume its final position and thereby connect ground directly to the winding of the back release relay PX. As soon as this connection is eiiected relays PX and J are placed in series. The windings of these relays are such, however, that relay J will operate in series with the winding oi" relay PX, while the latter relay will not operate through the winding of relay J. `The operation of relay J disconnects ground from. wire 35 leading to No. 9 set of contacts, but in its place connects the winding of relay I.

.As soon as the foregoing change takes place No. 9 set of contacts is rendered selectable and the next selector switch engaging this group of contacts will automatically step until No. 9 set of contacts are reached. As soon as these contacts are reached, relay I is energized in the same manner as relay J. The operation of relay I removes ground from No. 8 set of test contacts and in its place connects the winding of relay H.

rllhis method oi selection is continued until relay B is operated, whereupon No. l set ot contacts are rendered selectable. The operation of relay A when No. l set of contacts are selected, simply serves to prevent ground being connected to its associated test contacts. The busy condition of a contact after selection is determined by ground through the winding of a back release relay as PX.

From the foregoing description it will be seen that the first selectable contact will be No. 10 and in order for that contact to be selected it is necessary for the wipers to pass over all of the preceding contacts and to insure the contacts being kept clean and in constant use.

Ot course, during certain periods a trunk will be used and then released before another selection is completed, and in that event if No. 10 contact was the one selected y and released it will also be the one next selected. However, as a rule with the arrangement shown in Fig. l the contacts and trunks will be uniformly used. If it is assumed that the last trunk used or selected will be the last trunk released then the con tacts will be selected in rotation.

In Fig. 3 I have shown a modified arrangement, whereby when a trunk is selected it will render the preceding trunk selectable regardless of whether the selected trunk is released before the next selection occurs. y

Thel arrangement shown is almost identical with that of Fig. l, the only difference that each relay of the series A to J vof inclusive when operated is maintained locked to ground through the back contacts of the preceding relay.

IVe will assume that the first contact selected is No. 10. The operation of relay J associated with this contact will connect the winding of relay I to No. 9 set of contacts. If No. l0 trunk is released before the next selection, relay J will remain locked to ground through the back contacts oi relay I. rIhis ground connection is made through a high resistance coil JJ. This resistance is sufficient to maintain relay J energized without rendering the test contact busy. Relay J remaining energized even though its trunk is released allows No. 9 contact to be selected as ground is removed from that contact by the action oi." relay J. The next selector switch rotating to select an idle trunk in that group will select No. 9 contact and thereby operate relay I. The operation of relay I removes ground from the locking contact of relay'J, thereby allowing that relay to restore. The next selectable contact, however, will be No. 8 as relay I will remain energized until No. 8 contact is selected, regardless of whether No. 9 trunk associated with No. 9 contact is released or not.

The contacts for the designating or sociated contacts (Fig. make before break type. The same type of contacts can be applied to the corresponding relays, in Fig. l as such contacts are well known and commonly used.

For simplicity I have shown but one set complete circuits for the iirst selector and connector switches. Figs. l and 3 show groups of multiple contacts with their associated control relays. The contacts shown in Fig. l can represent the multiple contacts of a single group of selector switches 500, 600 and 700 while the contacts in Fig. 3 can represent those of different groups of switches. Of course, each set of multiple contacts has an associated connector switch as shown in Fig. 2.

In the present instance I have only shown iirst selector and connector switches but it will be understood that second selector switches can be interposed between the first selectors and connectors in manner.

When second selector switches are used, the bank contacts will be wired in the same manner as those of the lirst selectors. In other words each row of multiple contacts will be provided with its set of designating or control relays A. to J inclusive. y

In connection with Fig. 3, I have stated that the coil JJ is of high resistance so as not to render the test contact busy. Instead of simply using these series of coils AA. to JJ for holding their respective relays enershifting the windings of control relays to their as- 3) are shown as the the ordinary y ing Yassociated contacts, of means gized, they can be of low resistance to render their associated test contacts busy yagainst selection. ln this case the energization of a designating relay renders its associated contact busy against selection until it is designated by the test wiper of the selector switch and until afterftheV energization of the preceding designating relay of the series.

Having thus described my invention, what selected to render another of said contactsy selectable. 2. ln a telephone exchange system, the combination with an automatic switch having agroup of associated test contacts, one of said contacts only being normally selectable, of means associated withy said switch for selecting said conta-ct, means whereby when kthe particular contact is selected the preceding contact passed over by the switch in making the yselection is selectable, substantially as set forth.

3. ln a telephone exchange system, the combination with an automatic switch having a rowof associated test contacts,the last contactfin said row being normally selectable, for selecting the last said contact, means `whereby when the last contact is selected they preceding contact passed over by the switch in making the selection is then rendered selectable, ysubstantially as set forth. f

4f. In a telephone exchange system, the combination with an automatic switch having a row of associatedtest contacts, of means associated with said switch for selecting one of said contacts, means whereby when the particular contact is selected the preceding contact passed over by the switch yin making the selection is then renderedL selectable, substantially as set forth. 5. ln a telephone exchange system, the combination with an automatic switch having a row of associated test contacts,fof

means associated with said contacts whereby the first contact selectable by said switch .is the last contact in the row, means whereby when the last contact is selected the preceding contact passed over `by the switch in making the selection is then rendered selectable, substantially as set forth.

- 6.111 a telephone exchange system, the

combination with any automatic switch havpermanently associated with said contacts whereby when particulai contacts are selected they preceding contacts passed over by theswitch select said contact, and elecjciated with said switch then rendered y of means associated with said switch i brush yto wipe over said contacts, and means commsaaee combination with an automatic switch havf ing a row of associated contacts, certain of said contacts being unselectable incharacter while other of said contacts are selectable in character, means whereby when said switch engages a selectable contact one of said unselectable preceding contacts passedy over by the switch in engaging the selectable contact is then rendered selectable in character.

8. in a telephone exchange system, the combination with an automatic switch haying a row of test contacts, of means assofor selecting one of said contacts, means comprising a series of relays associated with and controlled over said contactsy for designating the contact to be next selected, substantially as set forth.

9. In a telephone exchange system, the combination with an automatic switch havassociated with said switch for selecting said contacts, means permanently associated with and controlled over said contacts for designating ythe contact to be selected by said switch, and `means for moving said switch into yengagement with said Contact, substantially as set forth.

l0.y In a telephone exchange system, the combination with kan automatic switch having associated contacts, said contacts being engageable by said switch, means permanently associated with and controlled over said contacts for designating the contact to be engaged by said switch, and means for moving said switch into engagement with said contact, substantially as set forth.

11. In a telephone exchange system, the combination with an automatic switch having a row of associated contacts, means comprising a series of relays controlled over said contacts for determining the contact to be selected by said switch, substantially as set forth.

12. In a telephone exchange system, the combination with an automatic switch having a row of associated contacts, of a test associated with said switch adapted prising a relayV adapted when said test brush 'selects a particular contact to render a contact previously wiped over selectable.

13. In a telephone exchange system, the

ing a row of associated contacts, of means combination with an automatic switch having associatedcontacts, of means compris- L ing a seriesr of relays rassociated with said contacts for rendering the contacts selectable in rotation by said switch, vsubstantially as set forth.

14. In a telephone exchange system, thek combination with a plurality of automatic switches,feach switch having associated multiple contacts, of means associated withY and Lacasse controlled over said contacts for rendering the contacts selectable for service in rotation by said switches, substantially as set forth.

15. In a telephone exchange system, the combination with an automatic switch, trunk lines terminating therein, a test terminal for each trunk, and means associated with said contacts whereby the rst contact selectable by said switch when all of the trunks are idle is the last contact in the row.

16. In a telephone exchange system, the combination with an automatic switch having a row of associated test contacts, means associated with said contacts whereby the first contact selectable by said switch is the last contact in the row, additional means whereby when the last contact is selected the preceding contact passed over by the switch in making the selection is then rendered selectable, substantially as set forth.

17. In a telephone exchange system, the combination with calling and called subscribers lines, automatic switching mechanism comprising trunk selecting and line selecting` switches for interconnecting said lines, contacts for said trunk selecting switches,means permanently associated with and controlled over said contacts for invariably causing said trunk selecting switches to select said line selecting switches in rotation.

18. In a telephone. exchange system, the combination with calling and called subscribers lines, selector and connector switches for inter-connecting said lines, of means for invariably causing selection for service of said connector switches in rotation by said selector switches for inter-connecting said lines, said means permanently associated with said connector switches and titties of this patent may be obtained for ve cents each,

directly controlled by said selector switches, substantially as set forth.

19. In a telephone exchange system, the combination with selector and connector switches, contacts for said connector switches at said selector switches, means permanently associated with and controlled over said contacts for invariably securing use of said connector switches in rotation by said selector switches, substantially as set forth.

20. The combination with the stations of a telephone exchange, of a plurality of switches less in number than the number of stations in the exchange, electrically operated means permanently associated one with each of said switches for causing the same to be selected invariably in a definite order, and means whereby an automatically selected one of said switches may be used in establishing a talking circuit between different stations.

2l. The combination with a series of movable main switches, a series of auxiliary switches, and electrically operated devices for moving a main switch to electrical connection with successive auxiliary switches, of means permanently associated with said switches for causing the same to be selected invariably in a denite order, and means by which the circuit for the electrically operated devices will be automatically broken when the moved main switch reaches connection to a designated auxiliary switch.

In testimony whereof I aix my signature in `presence of two witnesses.

JOSEPH Il. WRIGHT.,

by addressing the Commissioner ot' Fatenta,

Washington, D. G. 

